Identification of drought-inducible genes and differentially expressed sequence tags in barley

Abstract

Drought limits cereal yields in several regions of the world and plant water status plays an important role in tolerance to drought. To investigate and understand the genetic and physiological basis of drought tolerance in barley, differentially expressed sequence tags (dESTs) and candidate genes for the drought response were mapped in a population of 167 F8 recombinant inbred lines derived from a cross between "Tadmor" (drought tolerant) and "Er/Apm" (adapted only to specific dry environments). One hundred sequenced probes from two cDNA libraries previously constructed from drought-stressed barley (Hordeum vulgare L., var. Tokak) plants and 12 candidate genes were surveyed for polymorphism, and 33 loci were added to a previously published map. Composite interval mapping was used to identify quantitative trait loci (QTL) associated with drought tolerance including leaf relative water content, leaf osmotic potential, osmotic potential at full turgor, water-soluble carbohydrate concentration, osmotic adjustment, and carbon isotope discrimination. A total of 68 QTLs with a limit of detection score > or =2.5 were detected for the traits evaluated under two water treatments and the two traits calculated from both treatments. The number of QTLs identified for each trait varied from one to 12, indicating that the genome contains multiple genes affecting different traits. Two candidate genes and ten differentially expressed sequences were associated with QTLs for drought tolerance traits.

Genetic Analysis of Water Use Efficiency in Rice (Oryza sativa L.) at the Leaf Level

“…In rice, one to three QTLs for Δ 13 C were identified by Laza et al (2006) and Takai et al (2006), three to five by Price et al (2002), and four by Xu et al (2009). Up to seven QTLs were identified in Stylosanthes scabra (Thumma et al 2001), two to five in barley (Diab et al 2004;Ellis et al 2002;Teulat et al 2002), and four to five in Brassica oleracea (Hall et al 2005). In these studies, individual QTLs explained ≤30% of the phenotypic variation for Δ 13 C, consistent with results from the present study.…”

“…At a position corresponding to the QTL for Δ 13 C found on chromosome 8, several groups working on rice have found a QTL for osmotic adjustment (Kamoshita et al 2002;Robin et al 2003;Zhuang et al 2002). At the orthologous position corresponding to the QTL for Δ 13 C on rice chromosome 5, barley has a QTL for osmotic solute potential and watersoluble carbohydrates (associated with RFLP marker CDO202) on chromosome 1H (Diab et al 2004). The position of the ABA QTL (lABA12.1_E3) on rice chromosome 12 is orthologous to a region of barley chromosome 2H where two QTLs for Δ 13 C and a QTL for osmotic adjustment were identified (Teulat et al 2002) and to the homologous wheat chromosomes 2A and 2B where a QTL for osmotic solute potential was found (Diab et al 2004).…”

“…At the orthologous position corresponding to the QTL for Δ 13 C on rice chromosome 5, barley has a QTL for osmotic solute potential and watersoluble carbohydrates (associated with RFLP marker CDO202) on chromosome 1H (Diab et al 2004). The position of the ABA QTL (lABA12.1_E3) on rice chromosome 12 is orthologous to a region of barley chromosome 2H where two QTLs for Δ 13 C and a QTL for osmotic adjustment were identified (Teulat et al 2002) and to the homologous wheat chromosomes 2A and 2B where a QTL for osmotic solute potential was found (Diab et al 2004). In our case, no QTL for Δ 13 C colocalized with the QTL for ABA concentration on rice chromosome 12 (lABA12.1_E3), but the ABA QTL in our study appears to be in a homologous position with a QTL for Δ 13 C found by Laza et al (2006) in irrigated lowland rice.…”

“…The first QTLs associated with Δ 13 C were reported by Martin et al (1989) in tomato and since that time QTLs for Δ 13 C have been identified in rice (Price et al 2002) and several other plant species (Brendel et al 2002;Casasoli et al 2004;Diab et al 2004;Ellis et al 2002;Gleick 2003;Hausmann et al 2005;Masle et al 2005;Rebetzke et al 2008;Saranga et al 2004;Scalfi et al 2004;Specht et al 2001;Teulat et al 2002;Thumma et al 2001). Until now, all QTL studies conducted in rice involved segregating populations evaluated at different growth stages in field environments.…”

The draft genome of Tibetan hulless barley reveals adaptive patterns to the high stressful Tibetan Plateau

“…For example, a previously known drought stress-related quantitative trait locus (QTL), QRwc.TaEr-7H.2, which is associated with leaf relative water content, was found in selective sweep regions (SI Appendix, Fig. S21) (27). These results will facilitate crop improvement toward sustainable supplies of food, feed, and industry resources for people living on the highland and around the world.…”